Design and development of a near-IR integral field spectrograph for the HWO Coronagraph Instrument

The primary mission of the Habitable Worlds Observatory (HWO) is to identify and characterise potentially habitable worlds. Spectra across a wide wavelength range are needed to cover multiple spectral features per molecule of interest. An integral field spectrometer (IFS), fed by a coronograph system, can be used to measure spectra from any planets within the nulled field of the coronograph, while also characterizing the residual speckles as a function of wavelength, enabling the contrast ratio to be further enhanced. We present design trades for an infrared IFS (0.8 to 1.7 µm) for the HWO Coronagraph Instrument, including assessment of the relative merits of lenslet and image slicer based architectures. Key requirements include full sampling of the speckle field at all wavelengths, maximized optical throughput, and control of spectral cross talk and stray light. We identify technology developments needed to advance the instrument design to the required technology readiness level.